System for controlling combustion engine performance in accordance with driver behavior

ABSTRACT

A system for controlling internal combustion engine performance in accordance with driver behavior includes a vehicle control computer operable to receive a plurality of vehicle operating parameter signals and control engine fueling based thereon. In accordance with an operational status, or an operational state determined over a predefined time interval, of one or more of the vehicle operating parameter signals, the system is operable to control available engine performance. Both the operational status and operational state of the various vehicle operating parameters are the result of the manner in which the driver operates the vehicle. The control system of the present invention is thus operable to reward/penalize driver performance by correspondingly adding/subtracting available engine performance in the form of available engine output power and/or available vehicle speed. Preferably, subtracting available engine performance occurs automatically, and adding available engine performance may be either done automatically or according to driver demand.

REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.08/792,488, filed Jan. 31, 1997, now U.S. Pat. No. 5,954,617 andentitled: “System for Controlling Internal Combustion Engine Performancein Accordance with Driver Behavior”.

FIELD OF THE INVENTION

The present invention relates generally to systems for encouraging motorvehicle operators to achieve preset fuel economy goals, and morespecifically to such systems for controlling engine performance infurtherance of such goals.

BACKGROUND OF THE INVENTION

Motor vehicle fleets are typically formed of special purpose vehiclessuch as taxis, buses and sales/service vehicles, as well as productdelivery/shipping vehicles such as medium and heavy duty trucks, to namea few. Such fleet vehicles may or may not have different driversperiodically assigned thereto, and in any case the driving skills offleet drivers typically vary widely. Thus, while some drivers operatetheir fleet vehicles in a manner that is consistent with fleet vehicleoperating goals, others do not. Fleet owners and/or operators have thusdevised numerous techniques and systems to control and encourage properoperation of the fleet vehicles.

An example of one known approach for encouraging such proper operationof a fleet vehicle involves utilizing a trip recorder which is operableto collect vehicle and engine operating conditions during vehicleoperation. The vehicle and engine operating data is recorded ontosuitable media during vehicle operation, and is thereafter removed fromthe vehicle and downloaded by suitable means. A trip report is typicallygenerated from the downloaded data which is reviewed by the fleet ownerand/or manager. In cases where the trip report indicates that thedriver's performance meets or exceeds certain operating goals, such aspreestablished fleet duel economy goals, the driver becomes eligible forsome type performance award.

While the foregoing approach has been used in the past with somesuccess, it has several drawbacks associated therewith. For example, thedriver's award is typically received days and often weeks after thedriving performance. This delay tends to diminish the importance ofproper vehicle operation to many drivers. Moreover, the awards aretypically recognition type awards or cash/goods which do not relatedirectly to the operation of the vehicle. Further, this approach servesonly to reward drivers that operate the fleet vehicles in accordancewith certain fleet operating goals, and does not penalize drivingperformance that is inconsistent with such goals.

U.S. Pat. No. 5,394,336 to Lammers et al. addresses the first of theforegoing drawbacks by disclosing a satellite communication systemoperable to immediately notify and reward a driver that is operating avehicle in accordance with predetermined vehicle operating goals.However, such a system does not address either of the remaining exampledrawbacks discussed above.

U.S. Pat. No. 5,477,597 to Weisman et al. attempts to address the firsttwo of the drawbacks discussed above by disclosing a control systemwhich has an ultimate goal of maximizing fuel economy. The system isoperable to increase the vehicle speed available to the driver as fueleconomy increases, wherein the upper limit on the allowable vehiclespeed is increased proportionally to an amount that a threshold fueleconomy is exceeded. While such an increase in fuel economy is disclosedas possibly being the result of minimization of idle time, selection ofoptimum transmission gears, maintaining a steady throttle or reducingthe use of engine-driven accessory loads, “fuel economy” is measured inthe Weisman et al. system either in accordance with a trip average MPGor a filtered MPG value utilizing a lag calculation.

While the Weisman et al. system goes further in addressing the driverreward system drawbacks discussed hereinabove, it has its own drawbacksassociated therewith. For example, the Weisman et al. system disclosesonly adding vehicle speed to reward fuel economic vehicle operation, anddoes not address any type of penalization approach for deterring vehicleoperation resulting in poor fuel economy. Moreover, the Weisman et al.“fuel economy” calculations are quite limited in that they are basedsolely on MPG calculations. Further, the Weisman et al. system disclosesadding vehicle speed only and contains no mention of alternativelyadding to, or increasing, a different engine performance parameter.

U.S. Pat. No. 4,914,597 to Moncelle et al. addresses some of thedrawbacks discussed hereinabove in that it discloses a system foradjusting engine output power based on the operational status of avehicle cruise control system. Specifically, Moncelle et al. disclosesoperating the engine in accordance with a first set of engine outputtorque curves when cruise control is not engaged, and in accordance witha second set of higher engine output torque curves when cruise controlis engaged. However, while the Moncelle et al. system addresses some ofthe drawbacks associated with prior art systems as discussedhereinabove, this system also has shortcomings associated therewith. Forexample, the level of engine output power is based solely on theoperational status of the cruise control system and does not take intoaccount any other engine and/or vehicle operating parameter that mayaffect vehicle fuel economy. Moreover, this system, as with all otherprior art systems discussed above, fails to provide the fleetowner/manager with programming flexibility to set limits for the vehicleoperating parameters and/or driver rewards, choose among one or morevehicle operating parameters on which a driver reward/penalty is based,or choose between a number of possible engine and/or vehicleoperation-based performance rewards or penalties.

What is therefore needed is a flexible system for controlling engineperformance according to driver behavior. Such a system shouldpreferably reward compliance with predefined vehicle operational goalsand penalize noncompliance therewith, and should further preferablyprovide the fleet owner/manager with maximum flexibility in programmingparameters and parameter values associated with such a system.

SUMMARY OF THE INVENTION

Many of the shortcomings described in the BACKGROUND section areaddressed by the present invention. The present invention includes avehicle control computer operable to receive a plurality of vehicleoperating parameter signals and control engine fueling in accordancetherewith. Based on either an operational status, or operationalperformance over a predefined time interval, of one or more of thevehicle operating parameter signals, the control system of the presentinvention is operable to control available engine performance inaccordance therewith. Available engine performance may take the form ofavailable engine output power and/or available vehicle speed, as well asany of a number of alternative engine performance parameters. In anycase, both the operational status and operational performance of thevarious vehicle operating parameter signals are linked directly todriver behavior, i.e. the manner in which the driver operates thevehicle. Accordingly, the present invention is operable to increaseavailable engine performance if the operational status or operationalperformance of one or more of the vehicle operating parameter signals isconsistent with predefined vehicle operational goals, and to decreaseavailable engine performance if the operational status or operationalperformance of the one or more vehicle operating parameters isinconsistent with the predefined vehicle operational goals.

In accordance with one embodiment of the present invention, a functionalrelationship is established between an operational status, and/oroperational performance over a predefined time period, of one or more ofthe vehicle operating parameter signals and an engine performanceparameter such as engine output power and/or available vehicle speed.The one or more vehicle operating parameters, corresponding engineperformance parameter(s), and functional relationship therebetween areeither contained within a memory portion of the vehicle control computeror programmable therein by a fleet owner/manager. During subsequentvehicle operation, the one or more vehicle operating parameter signalsare monitored and available engine performance is automaticallyadjusted, by increasing or decreasing available engine performance,according to a comparison between the operational status and/oroperational performance of the one or more vehicle operating parametersignals and the established functional relationship.

In accordance with another embodiment of the present invention, afunctional relationship is established between an operational status,and/or operational performance over a predefined time period, of one ormore of the vehicle operating parameter signals and a time-basedreward/penalty for subsequent adjustment of an engine performanceparameter such as engine output power and/or available vehicle speed.The one or more vehicle operating parameters, corresponding engineperformance parameter(s), and functional relationship therebetween areeither contained within a memory portion of the vehicle control computeror programmable therein by a fleet owner/manager. During subsequentvehicle operation, the one or more vehicle operating parameter signalsare monitored and a performance time period is automatically accumulatedaccording to a comparison between the operational status and/oroperational performance of the one or more vehicle operating parametersignals and the established functional relationship. Preferably, anydecrease in available engine performance, corresponding to penalty timefor unacceptable driver performance, is instituted automatically for theduration of the penalty time. Any increase in available engineperformance, corresponding to reward time for acceptable or exceptionaldriver performance, may be either instituted automatically or mayaccumulate as available high performance engine operation time, andpreferably be displayed, as such in the cab area of the vehicle. Upondriver demand, high performance engine operation may then be selected.In this way, high performance engine operation may be “saved” forsituations in which the driver desires such high performance. One objectof the present invention is to provide an improved driver incentivesystem that automatically controls available engine performance inaccordance with driver behavior, thereby encouraging drivers to operatetheir vehicles in accordance with predefined vehicle operational goals.

Another object of the present invention is to provide such a systemwherein available engine performance is controlled by increasingavailable engine output power and/or available vehicle speed, or bycontrolling alternative engine performance parameters, as a reward foroperating the vehicle in accordance with the predefined operationalgoals, and by decreasing available engine output power and/or availablevehicle speed, or by controlling alternative engine performanceparameters, as a penalty for failing to operate the vehicle inaccordance with the predefined operational goals.

Yet another object of the present invention is to provide such a systemwherein a reward time period is awarded for acceptable or exceptionalvehicle operation and a penalty time period is assessed for unacceptablevehicle operation.

Still another object of the present invention is to provide such asystem wherein available engine performance is automatically decreasedbased on any accumulated penalty time, and available engine performanceis either automatically increased based on any accumulated reward time,or is increased upon driver demand therefore.

These and other objects of the present invention will become moreapparent from the following description of the preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic illustration of one embodiment of a controlsystem of the present invention for controlling internal combustionengine performance in accordance with driver behavior;

FIG. 2A is plot of engine power/vehicle speed versus a vehicle operatingparameter for controlling engine performance in accordance with oneembodiment of the present invention;

FIG. 2B is plot of engine power/vehicle speed versus a vehicle operatingparameter for controlling engine performance in accordance with anotherembodiment of the present invention;

FIG. 2C is plot of engine power/vehicle speed versus a vehicle operatingparameter for controlling engine performance in accordance with yetanother embodiment of the present invention;

FIG. 3A is a plot of vehicle speed differential versus a vehicleoperating parameter for controlling engine performance in accordancewith a further embodiment of the present invention;

FIG. 3B is a plot of vehicle speed differential versus a vehicleoperating parameter for controlling engine performance in accordancewith a yet a further embodiment of the present invention;

FIG. 3C is a plot of vehicle speed differential versus a vehicleoperating parameter for controlling engine performance in accordancewith a still a further embodiment of the present invention;

FIG. 4A is a diagrammatic illustration of an example in-cab display fordisplaying available increased engine performance time in accordancewith a still another embodiment of the present invention;

FIG. 4B is a diagrammatic illustration of an alternate example in-cabdisplay for displaying available increased engine performance timesimilar to the display illustrated in FIG. 4A;

FIG. 4C is a diagrammatic illustration of an optional in-cab display foruse in supplementing either of the displays illustrated in FIGS. 4A and4B;

FIG. 5 is a flowchart illustrating one embodiment of a softwarealgorithm for programming a vehicle control computer for operation inaccordance with the present invention;

FIG. 6 is a flowchart illustrating one embodiment of a softwarealgorithm for controlling engine performance in accordance with thepresent invention;

FIG. 7 is a flowchart illustrating another embodiment of a softwarealgorithm for programming a vehicle control computer for operation inaccordance with the present invention;

FIG. 8 is a flowchart illustrating one embodiment of a softwarealgorithm for controlling accumulated performance time in accordancewith the present invention; and

FIGS. 9A and 9B illustrate a flowchart of one embodiment of a softwarealgorithm for controlling engine performance based on accumulatedperformance time in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, such alterations and furthermodifications in the illustrated devices, and such further applicationsof the principles of the invention as illustrated therein beingcontemplated as would normally occur to one skilled in the art to whichthe invention relates.

Referring to FIG. 1, a control system 10 for controlling internalcombustion engine performance based on driver behavior, in accordancewith a preferred embodiment of the present invention, is shown. Centralto control system 10 is a control computer 12 which is preferably amicroprocessor-based vehicle control computer operable to control aplurality of engine and vehicle related functions as is known in theart. It is to be understood, however, that control computer 12 may beany known computer operable to receive one or more digital and/or analoginput signals, process these signals in accordance with a desiredalgorithm, and provide one or more corresponding digital and/or analogoutput signals. In one embodiment, control computer 12 includes aMotorola 68336 or equivalent microprocessor.

Control computer 12 further includes a memory 14 internal to controlcomputer 12 as shown, although the present invention contemplates thatadditional, or supplemental, memory may be provided external to controlcomputer 12 and operably connected thereto as is known in the art.Optionally, as will be discussed in greater detail hereinafter, controlcomputer 12 may include a clock or counter 16, although the presentinvention contemplates providing such a clock/counter external tocontrol computer 12 which is operably connected thereto as is known inthe art.

Control computer 12 includes a first input/output port I/O1 which isconnectable to a service/recalibration tool 18 via a number, n, ofsignal paths. Service/recalibration tool 18 is preferably a knownprogramming tool commonly used in the automotive industry forprogramming and/or reprogramming control computer 12 with calibrationinformation, software algorithms, and the like, without removing controlcomputer 12 from the vehicle. Control computer 12 also includes acommunications port COMM connected to an antenna 42 or similar signalreceiving/transmitting mechanism. A wireless communications device 44having an antenna 46 or similar signal receiving/transmitting mechanismis also included for one or two way communications with control computer12. Communications device 44 is preferably a known radiotransmitter/receiver, cellular telephone or the like, and is operable tosend and receive calibration information, software algorithms and thelike to control computer 12. In this manner, control computer 12 may beprogrammed or reprogrammed from a remote location and control computermay similarly send vehicle operational data, in real-time, to theremotely located communications device 44.

Control computer 12 includes a number of input ports capable ofreceiving digital and/or analog inputs from a variety of vehicle sensorsand systems as is known in the art, wherein computer 12 is operable toconvert any such analog signals to digital signals prior to processingthereof. For example, control system 10 includes a vehicle speed sensor20 which is operable to sense vehicle speed and provide a vehicle speedsignal corresponding thereto at input IN1 of control computer 12. Sensor20 is preferably a known sensor operable to sense rotational speed ofthe vehicle tailshaft (not shown), although the present inventioncontemplates utilizing other known sensor arrangements for determiningvehicle speed such as, for example, a wheel speed sensor. Control system10 further includes a vehicle cruise control system 22 which isoperable, as is known in the art, to automatically control vehicle speedabove a threshold vehicle speed. Cruise control system 22 is connectedto control computer 12 at input IN2, and provides a cruise controlstatus signal thereto corresponding to either an active or inactiveoperational status of the cruise control system 22. Control computer 12is responsive to the cruise control status signal, as well as othersignals provided thereto by cruise control system 22, to control enginefueling in accordance therewith.

A manually controlled throttle 24 is connected to input IN3 of controlcomputer 12, which is responsive to driver actuation thereof to controlengine fueling. Preferably, throttle 24 is a known electromechanicalthrottle pedal which is responsive to force applied thereto to provide acorresponding signal at IN3 indicative of throttle position orpercentage. In one embodiment, throttle 24 includes an idle validationswitch 26 associated therewith which is operable to provide a redundantsignal to input IN4 of control computer 12 indicative of either a“closed” or “open” throttle condition as is known in the art. Forexample, below a predefined position or percentage of throttle 24, idlevalidation switch 26 provides a signal indicative of a throttle “closed”condition which corresponds to an idle condition of the engine, andabove the predefined position or percentage of throttle 24, idlevalidation switch 26 provides a signal indicative of a throttle “open”condition.

Regardless of the mechanism by which engine fueling is controlled (i.e.either by manually actuated throttle 24 or cruise control system 22),control computer 12 provides an engine fueling signal at output OUTwhich is, in turn, connected to the fueling system 30 of internalcombustion engine 32. As is known in the art, a cruise control governorprovides the engine fueling signal in cruise control mode of operation,and a road speed governor provides the engine fueling signal undermanual throttle control. Preferably, engine 32 is a diesel engine foruse in a medium or heavy duty truck, although the present inventioncontemplates that engine 32 may be any internal combustion engine. Inany case, engine 32 includes a known engine speed sensor 34 connected toinput IN5 of control computer 12 which is operable to provide an enginespeed signal thereto.

Control computer 12 is operable to supply a fueling signal to fuelingsystem 30 according to throttle demand provided by either cruise controlsystem 22 or manually controlled throttle 24 as described hereinabove.In so doing, memory 14 of control computer 12 typically includes one ormore fueling rate calibrations, or maps, therein which control computer12 utilizes in providing a fueling rate signal to speed governor 28(either cruise control governor or road speed governor). Engine outputpower, or output torque, is defined by such fueling rate calibrations.The fueling rate signal is then processed by the appropriate speedgovernor and provided as a fueling signal to fueling system 30 of engine32. Either speed governor typically utilizes the engine speed signalprovided by engine speed sensor 34 as a feedback signal thereto forfurther controlling the fueling signal provided to fueling system 30 asis known in the art. Vehicle speed is thus typically controlled by acombination of the particular fueling rate calibration and appropriatespeed governor in response to a desired throttle position or percentageas commanded by either throttle 24 or cruise control system 22.

Engine 32 is connected to a transmission 36 which includes a pluralityof selectable gears that are engageable with a rotatable output shaft ofthe engine (not shown) as is known in the art. Transmission 36 mayinclude a number of manually selectable gears, in which case a gearshift lever 38 is typically positioned in the cab area of the vehicleand is mechanically coupled to transmission 36 via linkage L.Transmission 36 may further include a number of automatically selectablegears, wherein control computer 12 is operable, as is known in the art,to control the shifting of transmission 36 between such automaticallyselectable gears. Alternatively, transmission 36 may be a completelyautomated transmission, wherein gear shift lever 38 and linkage L areomitted, and wherein control computer 12 is operable to control alltransmission gear shifting. In the event that transmission 36 includesany such automatically selectable gears, control computer 12 includes aninput/output port I/O3 connected thereto via a number, j, of signalpaths. Control computer 12 is thus operable to control the automaticshifting of transmission 36 through at least some of these signal pathsas is known in the art.

Regardless of the particular type of transmission 36 used, controlcomputer 12 is preferably operable to determine which of the pluralityof selectable gears is presently engaged with the engine 32 by computinga ratio of engine speed, provided by engine speed sensor 34, to vehiclespeed, provided by vehicle speed sensor 20. Alternatively, transmission36 may be provided with a plurality of micro switches therein (notshown) which provide corresponding signals back to I/O3 of controlcomputer 12 indicative of the presently engaged transmission gear. As afurther alternative, transmission 36 may include a separatemicroprocessor-based computer operable to determine the presentlyengaged transmission gear in accordance with known techniques. Forexample, such a separate computer may be connected to some of the jsignal paths which comprise an SAE J1939 datalink. According to the SAEJ1939 bus industry standard, the control computer 12, as well as thecomputer associated with the transmission 36, may send and receivethereon data relating to the operational parameters of the engine,vehicle and/or transmission. With such an arrangement, the computerassociated with the transmission may receive signals from controlcomputer 12, via the J1939 datalink, which are indicative of vehiclespeed and engine speed, and proceed to compute the presently engagedtransmission gear from a ratio thereof, which information is thenprovided back to control computer 12 via the J1939 datalink. In anyevent, it is to be understood that the present invention contemplatesthat control computer 12 may use any known technique for determining thepresently engaged gear of transmission 36, as well as any knowntechnique for monitoring a shift sequence of transmission 36.

Control system 10 preferably further includes a display/interfacemonitor 40 located in the cab area of the vehicle which is connected tocontrol computer 12 at input/output port I/O2. Display/interface 40 isoperable to receive information from control computer 12, display suchinformation in real time, and include one or more driver actuatableswitches for sending certain commands back to control computer 12 aswill be discussed in greater detail hereinafter. While the presentinvention contemplates that any known display/interface device meetingthe above criteria may be used, display/interface device 40 ispreferably a RoadRelay™ monitoring and display device designed byCummins Engine Company, Inc. of Columbus, Ind., which is described inU.S. Pat. No. 5,303,163 entitled CONFIGURABLE VEHICLE MONITORING SYSTEM,which issued Apr. 12, 1994 to Ebaugh et al and is assigned to theassignee of the present invention, the contents of which areincorporated herein by reference.

In accordance with the present invention, control system 10 is operableto adjust available engine performance, by adjusting an engineperformance parameter, based on a comparison between one or more vehicleoperating parameters and predetermined operational states of the one ormore vehicle operating parameters. As used herein, the term “engineperformance parameter” is defined as engine output power (alternatively,engine output torque) or vehicle speed, wherein vehicle speed mayinclude any of manually controlled vehicle speed (via throttle 24),cruise controlled vehicle speed (via cruise control system 24) and/orgear down vehicle speed, or alternatively any of a number of performancerelated engine and/or vehicle operational parameters as will bedescribed in greater detail hereinafter. Gear down vehicle speed, asthis term is known in the art, refers to various vehicle speed rangesallowable by control computer 12 when engine 32 is engaged with any gearof transmission 36 other than the numerically highest, or “top,” gear.The term “available engine performance”, as used herein, is defined asan upper allowable limit of an engine performance parameter at any giventime. Thus, for example, for a maximum cruise controlled vehicle speedof 65 mph, the “engine performance parameter” refers to cruisecontrolled vehicle speed, and the “available engine performance” refersto a maximum cruise controlled vehicle speed of 65 mph. The term“adjusting” as it is used herein with reference to either “availableengine performance” or “engine performance parameter”, is defined aseither increasing or decreasing available engine performance or thevalue of the engine performance parameter, preferably in a manner asdiscussed hereinabove with respect to the fueling rate calibrationdeterminations, vehicle speed governor control, as well as engine idleshutdown, engine auto start/stop control, and progressive shiftingcontrol as will be described more fully hereinafter.

As described hereinabove, the term “engine performance parameter” isdefined as encompassing any of a number of performance related engineand/or vehicle operational parameters such as engine output power and/orvehicle speed. Another example of such a performance related operationalparameter is idle shutdown capability. As is known in the art, controlcomputer 12 may be configured to automatically shutdown the engine upondetection of a continuous engine idling condition for a predefined timeperiod. In accordance with the present invention, idle shutdowncapability may be disabled as a reward for desirable driver performance,and may be enabled as a penalty for undesirable driver performance.

An example of yet another performance related operational parameter isidle shutdown override capability. As in known in the art, idle shutdownsystems may be equipped with driver override capability. Such systemstypically provide some type of warning, such as flashing lights or thelike, some time prior to shutting down the engine. The driver may thendefeat idle shutdown by actuating the throttle pedal 24 and/or someother predefined vehicle device prior to actual engine shutdown. Inaccordance with the present invention, idle shutdown override may beautomatically enabled as a reward for desirable driver performance, ordisabled as a penalty for undesirable driver performance.

Still another example of a performance related operational parameter isidle capability during power-take-off (PTO) operation (known in the artas fast idle). As is known in the art, control computer 12 may beconfigured to either enable or disable engine idle during PTO operation.In accordance with the present invention, engine idle during PTOoperation may be enabled as a reward for desirable driver performance,or disabled as a penalty for undesirable driver performance.

Yet another example of a performance related operational parameter isone or more ambient air idle shutdown temperature limits. As is known inthe art, control computer 12 may be programmed to provide for differentengine idle shutdown operational modes depending on ambient temperature.By way of example, control computer 12 may be programmed with threetemperature limits wherein engine idle shutdown capability is disabledwhen ambient temperature is below the lowest temperature limit, thedriver has the ability to override idle shutdown, as discussedhereinabove, between the lower and middle temperature limits, engineshutdown capability is enabled and engine shutdown override capabilityis disabled between the middle and upper temperatures, and the drivermay again override engine shutdown above the upper temperature limit. Inaccordance with the present invention, the ambient air idle shutdowntemperature limits may be suitably modified as a reward for desirabledriver performance or as a penalty for undesirable driver performance.For example, as a reward for desirable driver performance, thetemperature range in which idle shutdown override capability is disabledmay be reduced. Conversely, as a penalty for undesirable driverperformance, the lower temperature limit below which idle shutdowncapability is disabled may be decreased to a lower temperature.

Still another example of a performance related operational parameter iseither a set point or hysteresis a range of a cab or bunk temperaturelimit below which the engine automatically starts to maintain the cab orbunk at a desired temperature level. As is known in the art, controlcomputer 12 may be programmed to automatically start and shutdown theengine in order to maintain certain engine and/or vehicle operatingparameters within predefined limits or ranges. One example vehicleoperating parameter is the interior cab or bunk temperature of a heavyduty truck. Below a programmed bunk temperature, the engine 32automatically starts so that the cab heating/cooling system (not shown)turns on to modulate the bunk temperature toward the predefinedtemperature level. Such a system typically has a programmed temperaturehysteresis defining a temperature range above and below the desired bunktemperature. In order to start or shutdown the engine 32, the actualbunk temperature must be outside the temperature hysteresis range. Inaccordance with the present invention, the desired temperature limit maybe raised during cold weather or lowered during warm weather, or thehysteresis temperature range may be reduced, as a reward for desirabledriver performance, and the desired bunk temperature may be loweredduring cold weather and raised during warm weather, or the hysteresistemperature range may be expanded, as a penalty for undesirable driverperformance.

Still a further example of a performance related operational parameteris progressive shifting capability or modification of progressiveshifting RPM limits. As is known in the art, control computer 12 may beconfigured to set upper engine RPM limits for each of the plurality ofselectable gears of transmission 36. Thus, in each of the selectabletransmission gears, the driver is permitted to increase engine RPM, viathrottle control as discussed hereinabove, up to a predefined engine RPMlimit, wherein such limits may be different for different transmissiongears. In accordance with the present invention, such progressiveshifting operation may be disabled, or the allowable engine RPM limitsincreased for desirable driver performance, and progressive shiftingoperation may be enabled, or the corresponding engine RPM limitslowered, for undesirable driver performance.

In each of the preceding examples, the driver reward or penalty isinstituted automatically depending on the status or performance historyof one or more “vehicle operating parameters”. The term “vehicleoperating parameter”, as used herein, is defined as anydriver-controllable operating parameter associated with the vehicleand/or engine that affects a predefined vehicle/engine performancevariable such as, for example, overall fuel economy The term “predefinedoperational state” of a vehicle operating parameter, as used herein, isdefined as either operation of the vehicle operating parameter within apredefined range of operational states thereof, and/or operation of thevehicle operating parameter below or above a predefined value of thevehicle operating parameter.

One example of a vehicle operating parameter monitored by control system10 is percentage of engine idle time. This parameter may be determinedin accordance with any of a number of techniques. According to onetechnique, control computer 12 continuously monitors an engine speedsignal provided to input IN5 by engine speed sensor 34. Any engine speedbelow a predefined engine speed defines an engine idling condition, andany engine speed above the predefined engine speed defines a non-idlingcondition of the engine. Control computer 12 is operable to computepercentage of engine idle time over a predefined time interval as thepercentage of time that the engine speed corresponds to an engine idlingcondition.

According to another technique for determining percentage of idle time,control computer 12 continuously monitors a throttle position signalprovided to input IN3 by throttle 24. Any throttle position below apredefined throttle position defines the engine idling condition, andany throttle position above the predefined throttle position defines anon-idling condition of the engine. Control computer 12 is operable tocompute percentage of engine idle time over a predefined time intervalas the percentage of time that the throttle position corresponds to anengine idling condition.

According to yet another technique for determining percentage of idletime, control computer 12 continuously monitors the status of idlevalidation switch 26 provided to input IN4 thereof. An active state ofthe idle validation switch 26 defines the engine idling condition, andan inactive state of switch 26 defines a non-idling condition of theengine. Control computer 12 is operable to compute percentage of engineidle time over a predefined time interval as the percentage of time thatthe idle validation switch 26 is active.

According to a further technique for determining percentage of idletime, control computer 12 continuously monitors a vehicle speed signalprovided thereto by vehicle speed sensor 20. Any vehicle speed below apredefined vehicle speed defines an engine idling condition, and anyvehicle speed above the predefined vehicle speed defines an enginenon-idling condition. Preferably, the predefined vehicle speed is set atzero mph, although the present invention contemplates other predefinedvehicle speeds as the idling condition vehicle speed threshold. In anyevent, control computer 12 is operable to compute percentage of idletime over a predefined time interval as the percentage of time that thevehicle speed corresponds to an engine idling condition.

It is to be understood that the present invention contemplates utilizingother known techniques for determining percentage of engine idling time.Regardless of the particular technique used, however, control system 10is operable to increase available engine performance if the percentageof engine idle time determined over a predefined time interval is lessthan a threshold value, and to decrease available engine performance ifthe percentage of engine idle time determined over the predefined timeinterval is greater than the threshold value. In this manner, driverswill be rewarded with increased engine performance for minimizing theirengine idle time, and will be conversely penalized for unacceptably highengine idle time with decreased engine performance. Since significantlyreducing engine idle time has a greater impact on fuel economy than doesa small, but noticeable, increase in available engine performance, theoverall fuel economy of the vehicle is increased by utilizing theconcepts of the present invention.

Another example of a vehicle operating parameter monitored by controlsystem 10 is the percentage of time that engine speed exceeds apredefined engine speed limit. In accordance with this example, controlcomputer 12 continuously monitors an engine speed signal provided toinput IN5 by engine speed sensor 34 as previously discussed. Controlcomputer 12 is operable to compute percentage of excessive engine speedtime over a predefined time interval as the percentage of time that theengine speed exceeds an excessive engine speed threshold. Control system10 is then operable to increase available engine performance if thepercentage of excessive engine speed time determined over a predefinedtime interval is less than a threshold value, and to decrease availableengine performance if the percentage of excessive engine speed timedetermined over the predefined time interval is greater than thethreshold value. Drivers are thus rewarded with increased engineperformance for minimizing excessive engine speed time, and areconversely penalized for frequently operating the vehicle at excessiveengine speeds.

Yet another example of a vehicle operating parameter monitored bycontrol system 10 is the distance traveled by the vehicle per unit offuel used by the engine, which parameter is preferably in the form of anaccumulated mile-per-gallon or trip mpg. In accordance with thisexample, control computer 12 continuously monitors fuel consumption anddistance traveled by the vehicle, using known techniques, and computes atrip mpg accordingly. Control system 10 is then operable to increaseavailable engine performance if the accumulated trip mpg is greater thana threshold value, and to decrease available engine performance if theaccumulated trip mpg is less than the threshold value. Drivers are thusrewarded with increased engine performance for fuel efficient vehicleoperation, and are conversely penalized for fuel inefficient vehicleoperation.

Still another example of a vehicle operating parameter monitored bycontrol system 10 is the time or distance of vehicle operation wherein anumerically highest gear of the transmission is engaged with the engine.In accordance with this example, control computer 12 continuouslycomputes the presently engaged transmission gear, utilizing one or moreof the techniques described hereinabove, and computes the percentage oftime over a predefined time interval, or percentage of distance of apredefined distance, that the numerically highest gear of thetransmission is engaged with the engine. Control system 10 is thenoperable to increase available engine performance if the percentage oftime (or distance) that the numerically highest gear of the transmissionis engaged with the engine over a predefined time (or distance) intervalis greater than a threshold value, and to decrease available engineperformance if the percentage of time (or distance) that the numericallyhighest gear of the transmission is engaged with the engine over thepredefined time (or distance) interval is less than the threshold value.As another example of an engine performance control which may be used inaccordance with the present invention, control system 10 may be operableto increase allowable vehicle speed only in one or more of the lowergears if the percentage of time (or distance) that the numericallyhighest gear of the transmission is engage with the engine over thepredefined time (or distance)interval is greater than the thresholdvalue. Conversely, control system 10 may be operable to decreaseallowable vehicle speed only in one or more of the lower gears if thepercentage of time (or distance) that the numerically highest gear ofthe transmission is engaged with the engine over the predefined time (ordistance) interval is less than the threshold value. In either case,drivers are thus rewarded with increased engine performance formaximizing operating time or distance in top gear, and are converselypenalized for excessively operating the vehicle in other than top gear.

A further example of a vehicle operating parameter monitored by controlsystem 10 is rapid deceleration. In accordance with this example,control computer 12 continuously monitors the vehicle speed signalprovided by vehicle speed sensor 20 at input IN1 thereof, and computesvehicle deceleration therefrom according to known techniques. Controlsystem 10 is then operable to increase available engine performance ifthe vehicle deceleration rate exceeds a predefined deceleration rateless than a predetermined number of times over a predefined time period,and decreases available engine performance if the vehicle decelerationrate exceeds the predefined deceleration rate more than thepredetermined number of times over the predefined time period. Driversare thus rewarded with increased engine performance for minimizing rapiddeceleration events, such as panic stops, and are conversely penalizedfor excessive numbers of rapid deceleration events.

Still a further example of a vehicle operating parameter monitored bycontrol system 10 is the average vehicle speed over a predefined timeinterval of engine and vehicle operation. In accordance with thisexample, control computer 12 continuously monitors the vehicle speedsignal provided by vehicle speed sensor 20 at input IN1 thereof, andincreases available engine performance if the average vehicle speed isbelow a predefined speed value, and decreases available engineperformance if the average vehicle speed is greater than the predefinedspeed value during engine and vehicle operation. Drivers are thusrewarded with increased engine performance for operating the vehiclebelow a predefined average vehicle, and are conversely penalized forexcessive average vehicle speed.

Still a further example of a vehicle operating parameter monitored bycontrol system 10 is vehicle acceleration rate. In accordance with thisexample, control computer 12 continuously monitors the vehicle speedsignal provided by vehicle speed sensor 20 at input IN1 thereof, andcomputes vehicle acceleration therefrom according to known techniques.Control system 10 is then operable to increase available engineperformance if the vehicle acceleration rate exceeds a predefinedacceleration rate less than a predetermined number of times over apredefined time period, and decreases available engine performance ifthe vehicle acceleration rate exceeds the predefined acceleration ratemore than the predetermined number of times over the predefined timeperiod. Drivers are thus rewarded with increased engine performance foroperating the vehicle according to fuel efficient acceleration rates,and are conversely penalized for operating the vehicle with excessiveacceleration rates.

Still a further example of a vehicle operating parameter monitored bycontrol system 10 is excessive proximity warnings. In accordance withthis example, the vehicle is equipped with a number of proximity sensors(not shown) which provide control computer 12 with proximity warningsignals when the vehicle comes excessively close to another object.Control computer 12 monitors the proximity sensors and increases engineperformance if less than a predefined number of proximity warningsignals are detected over a predetermined time interval, and decreasesengine performance if more than the predefined number of proximitywarning signals are detected over the predetermined time interval.Drivers are thus rewarded with increased engine performance for avoidingcollisions or rear collisions, and are conversely penalized withdecreased engine performance for excessive proximity warnings.

In accordance with another aspect of the present invention, a functionalrelationship is established between the predefined operational state ofthe vehicle operating parameter and a corresponding state or value ofthe engine performance parameter. The monitored value of the vehicleoperating parameter is then compared to this functional relationship indetermining the actual adjustment of the engine operating parameter. Oneembodiment of the present invention for providing such a functionalrelationship is illustrated in FIGS. 2A-2C which define available engineperformance as a direct function of the vehicle operating parameteraccording to a number of alternative techniques. Referring to FIG. 2A,one preferred technique for defining available engine performance 50 asa direct function of the vehicle operating parameter is shown. As shownin FIG. 2A, the vehicle operating parameter defines a threshold valuethereof between a low vehicle operating parameter value and a highvehicle operating parameter. Below this vehicle operating parameterthreshold, available engine performance 50 is set at a high levelthereof, and above the threshold available engine performance 50 is setat a low level thereof.

Referring now to FIG. 2B, an alternate technique for defining availableengine performance 52 as a direct function of the vehicle operatingparameter is shown. FIG. 2B includes two distinct vehicle operatingparameter threshold levels, threshold A and threshold B, between the lowand high values thereof. Below threshold A, available engine performance52 is set at a high level thereof. Between threshold A and threshold B,available engine performance 52 is set at a medium level thereof. Abovethreshold B, available engine performance 52 is set at a low levelthereof. While only two such vehicle operating parameter thresholdlevels are illustrated in FIG. 2B, it is to be understood that thepresent invention contemplates that any number of vehicle operatingparameter threshold levels may be used to define the functionalrelationship illustrated in FIG. 2B.

Referring now to FIG. 2C, another alternate technique for definingavailable engine performance 54 as a direct function of the vehicleoperating parameter is shown. FIG. 2C illustrates that the functionalrelationship between vehicle operating parameter and available engineperformance need not define a series of discrete engine performancelevels, but may rather define a continuous function 54 that decreaseswith increasing vehicle operating parameter values. It bears pointingout that the function illustrated in FIG. 2C need not be entirely linearas shown, but may alternatively be non-linear and/or piece-wise linear.

It is to be understood that while the available engine performancefunctions illustrated in FIGS. 2A-2C generally decrease as the vehicleoperating parameter value increases, the available engine performancefunctions could alternatively be made to generally increase as thevehicle operating parameter value increases. An example of a situationin which a decreasing function might be used is when the vehicleoperating parameter is percentage of engine idle time as discussedhereinabove. On the other hand, an example of a situation in which anincreasing function might be used is when the vehicle operatingparameter is trip mpg as discussed hereinabove.

Another embodiment of the present invention for defining a functionalrelationship between the predefined operational state of the vehicleoperating parameter and a corresponding value of the engine performanceparameter is shown in FIGS. 3A-3C which define available engineperformance, in the form of a speed delta variable, as a function of thevehicle operating parameter according to a number of alternativetechniques. In this embodiment, control system 10 is operable tocontinuously monitor the vehicle speed signal provided thereto at inputIN1 by vehicle speed sensor 20, and compute a learned speed therefromcorresponding to an average vehicle speed over a most recent timeperiod. If the instantaneous vehicle speed has decreased by apredetermined delta speed value from the learned speed and the throttledemand (provided by throttle 24 or cruise control system 22) is above apredefined throttle demand value, then control system 10 is operable tofuel the engine according to a higher horsepower fueling ratecalibration curve. This fueling technique is known and is intended tomaintain constant vehicle speeds through various road grade deviations.An example of a system employing one embodiment of the foregoingtechnique is disclosed in U.S. Pat. No. 5,343,780, entitled VARIABLEPOWER DRIVETRAIN ENGINE CONTROL SYSTEM, which issued Sep. 6, 1994 toMcDaniel et al. and is assigned to the assignee of the presentinvention, the contents of which are incorporated herein by reference.

In accordance with the present invention, the delta speed valuediscussed above may be made variable depending upon the performance ofone or more vehicle operating parameters. Generally, if the monitoredvehicle operating parameter values are consistent with vehicleoperational goals, the driver is rewarded with a smaller delta speedvalue, which corresponds to a smaller decrease in vehicle speed beforeswitching to higher engine horsepower capability. Conversely, if themonitored vehicle operating parameter values are not a consistent withvehicle operational goals, the driver is penalized with a larger deltaspeed value, which corresponds to a larger decrease in vehicle speedbefore switching to higher engine horsepower capability.

Referring to FIG. 3A, one preferred technique for defining availableengine performance in the form of a delta speed variable 60 as afunction of the vehicle operating parameter is shown. As shown in FIG.3A, the vehicle operating parameter defines a threshold value thereofbetween a low vehicle operating parameter value and a high vehicleoperating parameter. Below this vehicle operating parameter threshold,delta speed 60 is set at a low value thereof, and above this threshold,delta speed 60 is set at a high value thereof.

Referring now to FIG. 3B, an alternate technique for defining availableengine performance in the form of a delta speed variable 62 as afunction of the vehicle operating parameter is shown. FIG. 3B includestwo distinct vehicle operating parameter threshold levels, threshold Aand threshold B, between the low and high values thereof. Belowthreshold A, delta speed 62 is set at a low level thereof. Betweenthreshold A and threshold B, delta speed 62 is set at a medium levelthereof. Above threshold B, delta speed 62 is set at a high levelthereof. While only two such vehicle operating parameter thresholdlevels are illustrated in FIG. 3B, it is to be understood that thepresent invention contemplates that any number of vehicle operatingparameter threshold levels may be used to define the functionalrelationship illustrated in FIG. 3B.

Referring now to FIG. 3C, another alternate technique for definingavailable engine performance in the form of delta speed 64 as a functionof the vehicle operating parameter is shown. FIG. 3C illustrates thatthe functional relationship between vehicle operating parameter anddelta speed need not define a series of discrete delta speed levels, butmay rather define a continuous function 64 that increases withincreasing vehicle operating parameter values. It bears pointing outthat the function illustrated in FIG. 3C need not be entirely linear asshown, but may alternatively be non-linear and/or piece-wise linear.

It is to be understood that while the delta speed functions illustratedin FIGS. 3A-3C generally increase as the vehicle operating parametervalue increases, the delta speed functions could alternatively be madeto generally decrease as the vehicle operating parameter valueincreases. An example of a situation in which an increasing functionmight be used is when the vehicle operating parameter is percentage ofengine idle time as discussed hereinabove. On the other hand, an exampleof a situation in which a decreasing function might be used is when thevehicle operating parameter is trip mpg as discussed hereinabove.

Yet another embodiment of the present invention for defining afunctional relationship between the predefined operational state of thevehicle operating parameter and a corresponding value of the engineperformance parameter is shown in FIGS. 4A-4C which defines availableengine performance, in the form of award/penalization time, as afunction of the vehicle operating parameter. In this embodiment, controlsystem 10 is operable to award a predefined time period of increasedavailable engine performance if the monitored vehicle operatingparameter values are consistent with vehicle operational goals, andassess a predefined time period of decreased available engineperformance if the monitored vehicle operating parameter values are notconsistent with vehicle operational goals. Control system 10 mayautomatically increase/decrease available engine performance based on anaccumulated value of the award/penalization time in accordance with oneembodiment of the present invention. In another embodiment,display/interface 40 (FIG. 1) includes a driver actuatable high engineperformance switch 44 which provides the driver with the ability toselectively operate the vehicle with increased engine performance at thedriver's discretion, while the control system 10 is automaticallyoperable to decrease available engine performance based on anaccumulated penalization time amount. In this manner, the driver may“bank”, or accumulate, increased available engine performance time, andselect increased engine performance operation as needed or desired basedon road conditions or other criteria, whereas accumulated penalty timeis assessed automatically in the form of decreased engine performance.

Referring to FIG. 4A, one embodiment of a display 42 ofdisplay/interface 40 for controlling available engine performanceaccording to accumulated award/penalty time is shown. In the embodimentshown in FIG. 4A, display 42 provides, an indication of the amount oftime of increased available engine performance. At any time duringvehicle operation, the driver may actuate switch 44, in which casecontrol system 10 is operable to accordingly increase available engineperformance. In this embodiment, control computer 12 must include, orhave access to, a clock/counter 16 so that control computer 12 maydecrement the available increased available engine performance timewhile switch 44 is actuated. In the event that switch 44 is deactivated,or increased available engine performance time expires, control computer12 is operable to return available engine performance to its defaultvalue. Although FIG. 4A shows high performance operational timeavailable in hours and minutes, the present invention contemplates thatsuch high performance time may alternatively be accumulated anddisplayed in any combination of hours, minutes and/or seconds, or asavailable high performance distance (i.e. miles) available.

Referring now to FIG. 4B, an alternate embodiment of a display 43 ofdisplay/interface 40 is shown which displays an accumulated time valueof increased available engine performance, and further includes displayinformation relating to a value of awarded time (time award forincreased available engine performance) as well as a value ofpenalization time (time penalty for decreased available engineperformance). As illustrated in FIG. 4B, control computer 12 ispreferably operable to compute the accumulated time value of increasedavailable engine performance as simply the time awarded minus the timepenalized. However, the present invention further contemplates computingthe accumulated time value of increased available engine performanceaccording to other functions of award and penalization time. One exampleof such an alternative function might be to compute the accumulated timevalue of increased available engine performance as the time awardedminus twice the time penalized. It is intended that other functions maybe used to ultimately determine the accumulated time value of increasedavailable engine performance without detracting from the scope of thepresent invention.

Referring now to FIG. 4C, display/interface 40 may include an optionaldisplay 45 and corresponding optional switches 46 and 48. As illustratedin FIG. 4C, optional display 45 provides the driver with a choice of themanner in which the increased available engine performance may bemanifested. For example, display 45 includes, as increased availableengine performance options, either engine output power or vehicle speedas these terms are defined hereinabove. The driver may accordinglychoose to manifest any increased available engine performance asincreased engine power by actuating switch 46 in the presence of display45, or as increased vehicle speed by actuating switch 48 in the presenceof display 45.

In accordance with another aspect of the present invention, thefunctional relationships involving available engine performancediscussed hereinabove may include more than one vehicle operatingparameter. For example, the functional relationship between availableengine performance and vehicle operating parameter discussed withreference to FIGS. 2A-2C and 3A-3C may be defined as available engineperformance being a function of a number of logically connected vehicleoperating parameters. An example of such a multiple vehicle operatingparameter function is shown in Table I, which shows the resultingavailable engine performance adjustment in terms of adjustments in thevarious alternative available engine performance variables discussedhereinabove. While the only logical connector shown in Table I is theAND connector, it is to be understood that any of the known logicalconnectors, i.e. OR, NOR, NAND, etc., may be used to define the desiredfunctional relationship. It should further be understood that theparticular vehicle operating parameters and all numerical values listedin Table I are shown only for example purposes, and that any number andcombination of vehicle operating parameters discussed hereinabove may beused to define the functional relationship, and that any desirednumerical values may be used in defining such a functional relationship.

TABLE I Vehicle Speed Engine Speed Delta Power Trip MPG Logical IdleAdjust Adjust Available (mpg) Connector Time (%) (mph) (mph) (HP) ≧6.5AND ≦10 1.0 −1.0 370 ≧6.0 AND ≦20 0.0 0.0 350 ≧5.5 AND ≦30 −3.0 1.0 330≧5.0 AND ≦40 −5.0 2.0 330

As another example, the functional relationship between accumulatedavailable engine performance time and vehicle operating parameterdiscussed with reference to FIGS. 4A-4C may be defined as accumulatedavailable engine performance being a function of a number of logicallyconnected vehicle operating parameters. An example of such a multiplevehicle operating parameter function is shown in Table II, which showsthe resulting accumulated available engine performance time in terms ofminutes awarded/penalized. Again, while the only logical connector shownin Table II is the AND connector, it is to be understood that any of theknown logical connectors, i.e. OR, NOR, NAND, etc., may be used todefine the desired functional relationship. It should further beunderstood that the particular vehicle operating parameters and allnumerical values listed in Table II are again shown only for examplepurposes, and that any number and combination of vehicle operatingparameters discussed hereinabove may be used to define the functionalrelationship, and that any desired numerical values may be used indefining such a functional relationship.

TABLE II Time Trip MPG Logical Idle Time Award/Penalty (mpg) Connector(%) (minutes) ≧6.5 AND ≦10 5.0 ≧6.0 AND ≦20 0.0 ≧5.5 AND ≦30 −7.0 ≧5.0AND ≦40 −15.0

While the present invention contemplates that all vehicle operatingparameters, engine performance parameters and functional relationshipstherebetween, as well as all numerical values associated therewith, maybe provided in memory 14 (FIG. 1) by the vehicle manufacturer, suchvalues are preferably programmable into memory 14 via theservice/recalibration tool 18 by, for example, the fleet owner/manager.This feature of the present invention provides the fleet owner/managerwith the flexibility to tailor available engine performance to theparticular needs and goals of the fleet.

Referring now to FIG. 5, a flowchart is shown illustrating oneembodiment of a software algorithm 100 for programming memory 14 ofcontrol computer 12 for subsequent operation of control system 10 inaccordance with either of the embodiments illustrated in FIGS. 2A-2C and3A-3C. Algorithm 100 starts at step 102 and at step 104, a vehicleoperating parameter is input into memory 14 of control computer 12.Thereafter at step 106, algorithm 100 tests whether multiple vehicleoperating parameters are required. If so, algorithm execution continuesat step 108, and if only a single vehicle operating parameter isrequired, algorithm execution continues at step 110. If multiple vehicleoperating parameters are required, algorithm 100 tests, at step 108,whether all vehicle operating parameters have been input or whether morevehicle operating parameters are required. If more vehicle operatingparameters are required at step 108, algorithm execution loops back tostep 104 where an additional vehicle operating parameter is programmedinto memory 14 of control computer 12.

If no additional vehicle operating parameters are required at step 108,or if only a single vehicle operating parameter is required at step 106,the engine performance parameter is programmed into memory 14 at step110. As discussed hereinabove, the engine performance parameter may, inaccordance with the present invention, be one of engine output power orvehicle speed. Thereafter at step 112, a functional relationship betweenall vehicle operating parameters and the engine performance parameter,as discussed hereinabove, is programmed into memory 14 of controlcomputer 12.

Algorithm 100 may optionally continue from step 112 to step 114 where aminimum allowable value for the engine performance parameter isprogrammed into memory 14 of control computer 12. Algorithm executioncontinues from step 114, or from step 112 if step 114 is not included,to step 116 where algorithm execution is returned to its callingroutine, or to an algorithm managing portion of control computer 12. Inaccordance with yet another aspect of the present invention, step 114may be included to establish a minimum value of the engine performanceparameter below which available engine performance may not be adjusted.In this manner, control system 10 is programmed to achieve at least apredefined fuel economy level regardless of subsequent driver operationof the vehicle. In operation of the vehicle, the driver may be rewardedwith increased available engine performance for operating the vehicle inaccordance with predefined vehicle operational goals, and may bepenalized with decreased available engine performance for operating thevehicle in a manner that is not consistent with the predefined vehicleoperational goals as discussed herein. However, in accordance with thepresent aspect of the invention, available engine performance may not bedecreased below a predefined level of available engine performance sothat even the most poorly performing drivers will be guaranteed at leasta minimum level of available engine performance.

Referring now to FIG. 6, a flowchart is shown illustrating oneembodiment of a software algorithm 150 for operating control system 10in accordance with either of the embodiments illustrated in FIGS. 2A-2Cand 3A-3C. Preferably, algorithm 150 executes several times per secondto thereby continuously monitor vehicle operation parameter values orstates and adjust available engine performance according to the conceptsdescribed herein. Algorithm 150 starts at step 152, and at step 154determines a present operational state or value, in a manner discussedhereinabove, of one of the vehicle operating parameters established byalgorithm 100 of FIG. 5. Thereafter at step 156, algorithm 150 testswhether multiple vehicle operating parameters were programmed intomemory 14. If not, algorithm execution continues at step 160. Ifmultiple vehicle operating parameters are required, algorithm executioncontinues at step 158 where algorithm 150 tests whether operationalstates or values for all vehicle operating parameters have beendetermined. If not, algorithm execution loops back to step 154 where anoperational state or value of another vehicle operating parameter isdetermined by control system 10.

If only single vehicle operating parameter is detected as being requiredat step. 156, or if operational states or values have been determinedfor all vehicle operating parameters at step 158, algorithm executioncontinues at step 160 where a value for the engine performance parameterprogrammed in memory 14 is determined in accordance with the presetfunctional relationship between the engine performance parameter and theone or more vehicle operating parameters. Thereafter at step 162,control computer 12 adjusts the engine performance parameter accordingto the engine performance parameter value determined at step 160 tothereby establish the available engine performance level of subsequentoperation of engine 32. Thereafter at step 164, algorithm executionreturns to its calling routine.

Referring now to FIG. 7, a flowchart is shown illustrating oneembodiment of a software algorithm 200 for programming memory 14 ofcontrol computer 12 for subsequent operation of control system 10 inaccordance with the embodiment illustrated in FIGS. 4A-4C. Algorithm 200starts at step 202, and at step 204 a vehicle operating parameter isinput into memory 14 of control computer 12. Thereafter at step 206,algorithm 200 tests whether multiple vehicle operating parameters arerequired. If so, algorithm execution continues at step 208, and if onlya single vehicle operating parameter is required, algorithm executioncontinues at step 210. If multiple vehicle operating parameters arerequired, algorithm 200 tests, at step 208, whether all vehicleoperating parameters have been input or whether more vehicle operatingparameters are required. If more vehicle operating parameters arerequired at step 208, algorithm execution loops back to step 204 wherean additional vehicle operating parameter is programmed into memory 14of control computer 12.

If no additional vehicle operating parameters are required at step 208,or if only a single vehicle operating parameter is required at step 206,a functional relationship between all vehicle operating parameters andengine performance award/penalty time is programmed into memory 14 atstep 210. Thereafter at step 212, a time value of accumulatedperformance time is programmed into memory 14. In accordance with yetanother aspect of the present invention, performance time is permittedto accumulate within any given trip, and from trip to trip. Sincedrivers of fleet vehicles do not necessarily drive the same vehicle tripafter trip, step 212 provides the fleet owner/manager with theflexibility to provide any driver's current vehicle with that driver'saccumulated performance time value. Moreover, step 212 provides thefleet owner/manager with further flexibility to program “bonus” awardtime, assess additional penalty time or reset the accumulatedperformance time value for reasons which may be related or unrelated todriver performance.

From step 212, algorithm execution continues to step 214 where anincremental time award value for increased engine output power isprogrammed into memory 14. Thereafter at step 216, an incremental timeaward value for increased vehicle speed is programmed into memory 14.Steps 214 and 216 are intended for operation of control system 10 inaccordance with the display/interface embodiment of FIG. 4C wherein thedriver is permitted to select between available engine output power andavailable vehicle speed as the performance enhancement reward. Thoseskilled in the art will recognize that a corresponding one of steps 214and 216 may be omitted if such a driver option is not included.

From step 216, algorithm execution continues at step 218 where a penaltyengine performance parameter and corresponding time penalty thereforeare programmed into memory 14. Step 218 thus provides the fleetowner/manager with further flexibility in that the penalty engineperformance parameter input thereat may be different than the rewardengine performance parameter input at either of steps 214 or 216. As anoperational example, a programmer may wish to reward the driver with anincrease in available vehicle speed and penalize the driver with adecrease in available engine output power.

From step 218, algorithm execution continues at step 220 wherein afunctional relationship between accumulated performance time and theaward and penalty times is programmed into memory 14. As discussedhereinabove, this functional relationship may be as simple as asubtraction of penalty time from award time, or may be some other morecomplicated function of the award/penalty times. In any case, algorithmexecution continues from step 220 to step 222 where algorithm executionis returned to its calling routine.

Referring now to FIG. 8, a flowchart is shown illustrating oneembodiment of a software algorithm 250 for monitoring one or morevehicle operating parameters and computing accumulated award/penaltytime in accordance with the embodiment illustrated in FIGS. 4A-4C.Preferably, algorithm 250 executes several times per second to therebycontinuously monitor vehicle operating parameters and computeaccumulated award/penalty time according to the concepts describedherein. Algorithm 250 starts at step 252, and at step 254 determines apresent operational state or value, in a manner discussed hereinabove,of one of the vehicle operating parameters established by algorithm 200of FIG. 7. Thereafter at step 256, algorithm 250 tests whether multiplevehicle operating parameters were programmed into memory 14. If not,algorithm execution continues at step 260. If multiple vehicle operatingparameters are required, algorithm execution continues at step 258 wherealgorithm 250 tests whether operational states or values for all vehicleoperating parameters have been determined. If not, algorithm executionloops back to step 254 where an operational state or value of anothervehicle operating parameter is determined by control system 10.

If only single vehicle operating parameter is detected as being requiredat step 256, or if operational states or values have been determined forall vehicle operating parameters at step 258, algorithm executioncontinues at step 260 where a value for the engine performance award orpenalty is determined according to the functional relationshiptherebetween which was established in the programming algorithm of FIG.7. Thereafter at step 262, control computer 12 adjusts the accumulatedperformance time according to the computation resulting from step 260and according to the functional relationship between accumulatedperformance time and award/penalty times previously programmed intomemory 14. Thereafter at step 264, algorithm execution is returned toits calling routine.

Referring now to FIGS. 9A and 9B, a flowchart is shown illustrating oneembodiment of a software algorithm 275 for operating control system 10in accordance with the embodiment illustrated in FIGS. 4A-4C.Preferably, algorithm 275 executes several times per second to therebycontinuously monitor display/interface 40 and adjust available engineperformance according to the accumulated performance time. Algorithm 275starts at step 276, and at step 278 control computer 12 tests the valueof accumulated performance time. If, at step 278, the accumulatedperformance time is equal to a predetermined value, preferably zero,algorithm execution continues at step 280 where all engine performanceparameters defined in the programming algorithm of FIG. 7 are set totheir default values. If, at step 278, the accumulated performance timeis not equal to zero, or after execution of step 280, control computeragain tests the value of the accumulated performance time at step 282.If, at step 282, accumulated performance time is less than a predefinedvalue, preferably zero, algorithm execution continues at step 284 wherethe penalty engine performance parameter is set to the penalty value,wherein the penalty engine performance parameter and the penalty valuehave been previously programmed into memory 14. Coincident with theexecution of step 284, the real time is added to the accumulatedperformance time according to the real time clock/counter 16. In thismanner, penalty engine performance is decreased for the duration thatthe accumulated performance time is less than zero, which durationcorresponds to penalty time assessed by the functional relationshipestablished between accumulated performance time and a penalty timevalue that is programmed into memory 14, an example of which is setforth in Table II above.

If, at step 282, accumulated performance time is greater than or equalto zero, or after execution of step 284, algorithm execution continuesat step 286 where accumulated performance time is once more tested. If,at step 286, accumulated performance time is greater than zero,algorithm execution continues at step 288. If accumulated performancetime is less than or equal to zero at step 286, algorithm executioncontinues at step 302 where the display/interface 40 and accumulatedperformance time is updated with present values thereof. An accumulatedperformance time of greater than zero corresponds, as discussedhereinabove, to an award time of increased engine performance whichremains accumulated until driver selection thereof.

At step 288, control computer 12 tests whether high engine performanceoperation has been selected by the driver which, in one embodiment,corresponds to driver actuation of switch 44 of FIGS. 4A-4C. It is to beunderstood, however, that the driver may alternatively select suchincreased engine performance by actuating an equivalent switch locatedat some convenient location within the cab area of the vehicle.

In any event, if high engine performance operation has not been selectedat step 288, algorithm execution continues at step 302. If, on the otherhand, high engine performance operation has been selected at step 288,algorithm execution continues at step 290 where control computer 12tests whether the desired engine performance parameter for increasedengine performance operation is available engine output power oravailable vehicle speed which, in one embodiment, corresponds to driveractuation of either switch 46 or 48 respectively of FIG. 4C. However, aswith switch 44, it is to be understood that the driver may alternativelyselect between such manifestation of increased engine performance byactuating equivalent switches located at some convenient location withinthe cab area of the vehicle. In any case, if, at step 290, the desiredengine performance parameter is increased available engine output power,the algorithm execution continues at step 292 where the engineperformance parameter is set equal to engine output power. If, at step290, the desired engine performance parameter is increased availablevehicle speed, algorithm execution continues at step 294 where theengine performance parameter is set equal to vehicle speed.

Algorithm execution continues from either of steps 292 or 294 to step296 where control computer 12 increases the engine performance parameterto the award value previously programmed into memory 14 and beginsincrementally removing real time from the accumulated performance timeas discussed hereinabove. Real time clock/counter 16 continues to removetime from the accumulated performance time until the accumulatedperformance time reaches zero or the driver deactuates switch 44.

From step 296, algorithm execution continues at step 298 where controlcomputer 298 tests whether the currently increased engine performancehas an adverse impact on any of the currently monitored vehicleoperating parameter values. If not, algorithm execution continues atstep 302. If so, however, control computer 12 is operable to temporarilyhalt execution of the vehicle parameter monitoring routine of FIG. 8 forthe duration of increased engine performance operation. Algorithmexecution continues therefrom at step 302. From step 302, algorithmexecution loops back to step 278 where algorithm 275 restarts.

Steps 298 and 300 are intended to deal with the situation whereby adriver is rewarded for operation of the vehicle in accordance withvehicle operational goals, yet the reward, in the form of eitherincreased available engine output power or increased available vehiclespeed, causes the vehicle to operate in a manner inconsistent with thevehicle operational goals. Without steps 298 and 300, such anoperational reward may lead directly to an operational penalty asdiscussed hereinabove. Steps 298 and 300 ensure that such a penalty doesnot result by temporarily halting algorithm 250 of FIG. 8.

The present invention is illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiments have been shown and described and thatall changes and modifications that come within the spirit of theinvention are desired to be protected. For example, the flowcharts ofFIGS. 5-9B are intended to illustrate example algorithms for carryingout some of the concepts of the present invention described therein.Those skilled in the art will recognize that other algorithms differentin structure can be devised to carry out the same functions describedtherein without detracting from the scope of the present invention.

What is claimed is:
 1. A system for controlling internal combustion engine performance in a motor vehicle, comprising: means for monitoring a vehicle operating parameter; means for determining a percentage of time of a predetermined time interval of motor vehicle operation at which said vehicle operating parameter maintains a predefined operational state thereof; and means for adjusting available engine performance in accordance with said percentage of time at which said vehicle operating parameter maintains said predefined operational state thereof.
 2. The system of claim 1 wherein said means for adjusting available engine performance includes means for increasing and decreasing one of available engine output power and available vehicle speed.
 3. The system of claim 2 wherein the vehicle includes a throttle responsive to manual control thereof to control vehicle speed and a cruise control system operable to automatically control vehicle speed; and wherein said means for increasing and decreasing available vehicle speed includes means for increasing and decreasing any of a maximum manual throttle controlled vehicle speed, a maximum cruise controlled vehicle speed and a maximum gear down vehicle speed.
 4. The system of claim 1 wherein said means for monitoring a vehicle operating parameter includes means for sensing vehicle speed and producing a vehicle speed signal corresponding thereto; and wherein said predefined operational state of said vehicle operating parameter corresponds to a range of vehicle speed signals indicative of an engine idling state.
 5. The system of claim 4 wherein said means for adjusting available engine performance includes means for increasing available engine performance if said percentage of time of said predetermined time interval of motor vehicle operation at which said vehicle speed signal indicates an engine idling state is less than a predefined percentage, and for decreasing available engine performance said percentage of time of said predetermined time interval of motor vehicle operation at which said vehicle speed signal indicates an engine idling state is more than said predefined percentage.
 6. The system of claim 5 further including means for determining an average distance traveled by the vehicle per unit of fuel used by the vehicle; and wherein said means for increasing available engine performance includes the conditional that said average distance traveled by the vehicle per unit of fuel used by the vehicle is above a predefined fuel usage level, and said means for decreasing available engine performance includes the conditional that said average distance traveled by the vehicle per unit of fuel used by the vehicle is below said predefined fuel usage level.
 7. The system of claim 1 wherein the vehicle includes a transmission having a plurality of selectable gears operatively connected to the engine; and wherein said means for monitoring a vehicle operating parameter includes means for determining which, if any, of the plurality of selectable transmission gears are presently engaged with the engine and producing a gear engaged signal corresponding thereto; and wherein said predefined operational state of said vehicle operating parameter corresponds to a gear engagement signal indicative of engagement of a numerically highest one of the plurality of transmission gears with the engine.
 8. The system of claim 7 wherein said means for adjusting available engine performance includes means for increasing available engine performance if said percentage of time of said predetermined time interval of motor vehicle operation at which said gear engagement signal indicates engagement of said numerically highest gear is more than a predefined percentage, and for decreasing available engine performance if said percentage of time of said predetermined time interval of motor vehicle operation at which said gear engagement signal indicates engagement of said numerically highest gear is less than said predefined percentage.
 9. The system of claim 1 wherein the vehicle includes a cruise control system operable in an active state thereof to automatically control vehicle speed; and wherein said means for monitoring a vehicle operating parameter includes means for monitoring an operational status of said cruise control system and producing a cruise control status signal corresponding thereto; and wherein said predefined operational state of said vehicle operating parameter corresponds to a cruise control status signal indicative of an active state of said cruise control system.
 10. The system of claim 9 wherein said means for adjusting available engine performance includes means for increasing available engine performance if said percentage of time of said predetermined time interval of motor vehicle operation at which said cruise control status signal indicates an active state of said cruise control system is more than a predefined percentage, and for decreasing available engine performance if said percentage of time of said predetermined time interval of motor vehicle operation at which said cruise control status signal indicates an active state of said cruise control system is less than said predefined precentage.
 11. A method of controlling internal combustion engine performance in a motor vehicle, comprising the steps of: monitoring at least one vehicle operating parameter; determining an operating characteristic of said at least one vehicle operating parameter over a predefined time interval of vehicle operation; increasing available engine performance if said operating characteristic of said at least one vehicle operating parameter over said predefined time interval is consistent with a predetermined vehicle fuel economy goal; and decreasing available engine performance if said operating characteristic of said at least one vehicle operating parameter over said predefined time interval is inconsistent with said predetermined vehicle fuel economy goal.
 12. The method of claim 11 wherein said increasing available engine performance step includes increasing one of available engine output power and available vehicle speed; and wherein said decreasing available engine performance step includes decreasing one of available engine output power and available vehicle speed.
 13. The method of claim 12 wherein the vehicle includes a vehicle speed sensor operable to sense vehicle speed; and wherein said at least one vehicle operating parameter includes vehicle speed; and wherein said determining step includes determining a percentage of time of said predefined time interval that said vehicle speed corresponds to an engine idling condition.
 14. The method of claim 13 wherein said increasing step includes increasing available engine performance if said percentage of time of said predefined time interval that said vehicle speed corresponds to an engine idling condition is less than a predefined percentage; and wherein said decreasing step includes decreasing available engine performance if said percentage of time of said predefined time interval that said vehicle speed corresponds to an engine idling condition is greater than said predefined percentage.
 15. The method of claim 14 wherein the vehicle includes means for determining an average distance traveled by the vehicle per unit of fuel used by the vehicle; and wherein the method further includes the step of determining an average distance traveled by the vehicle per unit of fuel used by the vehicle; and wherein the step of increasing available engine performance is further conditioned upon said average distance traveled by the vehicle per unit of fuel used by the vehicle being above a predefined fuel usage level; and wherein the step of decreasing available engine performance is further conditioned upon said average distance traveled by the vehicle per unit of fuel used by the vehicle being below said predefined fuel usage level.
 16. The method of claim 12 wherein the motor vehicle includes a transmission operatively connected to the engine and having a plurality of gears selectably engageable with the engine; and wherein said at least one vehicle operating parameter includes presently engaged transmission gear; and wherein said determining step includes determining a percentage of time of said predefined time interval that said presently engaged transmission gear corresponds to a numerically highest one of the plurality of transmission gears.
 17. The method of claim 16 wherein said increasing step includes increasing available engine performance if said percentage of time of said predefined time interval that said presently engaged transmission gear corresponds to a numerically highest one of the plurality of transmission gears is greater than a predefined percentage; and wherein said decreasing step includes decreasing available engine performance if said percentage of time of said predefined time interval that said presently engaged transmission gear corresponds to a numerically highest one of the plurality of transmission gears is less than said predefined percentage.
 18. The method of claim 12 wherein the motor vehicle includes a cruise control system operable to automatically control vehicle speed; and wherein said at least one vehicle operating parameter includes cruise control status; and wherein said determining step includes determining a percentage of time of said predefined time interval that said cruise control system is active to thereby automatically control vehicle speed.
 19. The method of claim 18 wherein said increasing step includes increasing available engine performance if said percentage of time of said predefined time interval that said cruise control system is active is greater than a predefined percentage; and wherein said decreasing step includes decreasing available engine performance if said percentage of time of said predefined time interval that said cruise control system is active is less than said predefined percentage.
 20. A system for controlling internal combustion engine performance in a motor vehicle, comprising: means for monitoring a vehicle operating parameter and producing a vehicle operating parameter signal corresponding to an operational state thereof; and a control computer responsive to said vehicle operating parameter signal to increment a performance parameter by a first value if said operational state of said vehicle operating parameter signal is consistent with a predefined fuel economy goal for a first predetermined time period of vehicle operation, and to decrement said performance parameter by a second value if said operational state of said vehicle operating parameter signal is inconsistent with said predefined fuel economy goal for a second predetermined time period of vehicle operation, said control computer adjusting available engine performance in accordance with an accumulated value of said performance parameter.
 21. The system of claim 20 further including means responsive to driver actuation for selecting increased available engine performance and producing a performance signal corresponding thereto; and wherein said control computer is responsive to said performance signal to increase available engine performance if said accumulated value of said performance parameter is greater than a first predefined performance parameter value.
 22. The system of claim 21 wherein said control computer is further operable to automatically decrease available engine performance if said accumulated value of said performance parameter is below a second predefined performance parameter value.
 23. The system of claim 22 wherein said control computer includes means for adjusting available engine performance by increasing and decreasing one of available engine output power and available vehicle speed.
 24. The system of claim 23 further including means for displaying a current accumulated value of said performance parameter.
 25. The system of claim 24 wherein said means for displaying includes said means responsive to driver actuation for selecting increased available engine performance.
 26. The system of claim 25 wherein said means for displaying further includes means for permitting the driver to choose between said available engine output power and said available vehicle speed for increasing said available engine performance.
 27. The system of claim 20 further including means for displaying a current accumulated value of said performance parameter.
 28. A system for controlling internal combustion engine performance in a motor vehicle, comprising: means for monitoring a vehicle operating parameter and producing a vehicle operating parameter signal corresponding to an operational state thereof; and a control computer responsive to said vehicle operating parameter signal to award a credit corresponding to a predefined interval of higher available engine performance if said operational state of said vehicle operating parameter signal is consistent with a predefined fuel economy goal for a first predetermined interval of vehicle operation, said control computer accumulating said credits and adjusting available engine performance in accordance with the cumulative credit value.
 29. The system of claim 28 further including means responsive to driver actuation for selecting increased available engine performance and producing a performance signal corresponding thereto; and wherein said control computer is responsive to said performance signal to increase available engine performance if said cumulative credit value is greater than a first predefined value.
 30. The system of claim 29 wherein said control computer includes means for adjusting available engine performance by increasing and decreasing one of available engine output power and available vehicle speed.
 31. The system of claim 30 further including means for displaying the current cumulative credit value.
 32. The system of claim 31 wherein said means for displaying includes said means responsive to driver actuation for selecting increased available engine performance.
 33. The system of claim 32 wherein said means for displaying further includes means for permitting the driver to choose between said available engine output power and said available vehicle speed for increasing said available engine performance.
 34. The system of claim 28 further including means for displaying the current cumulative credit value.
 35. The system of claim 28 wherein said control computer is further responsive to said vehicle operating parameter signal to assess a penalty corresponding to a predefined interval of lower available engine performance if said operational state of said vehicle operating parameter signal is inconsistent with said predefined fuel economy goal for a second predetermined interval of vehicle operation, said control computer accumulating said penalties and adjusting available engine performance as a function of the cumulative penalty value and the cumulative credit value.
 36. The system of claim 35 wherein said control computer is further operable to automatically decrease available engine performance if said cumulative penalty value is above a second predefined value.
 37. A system for controlling internal combustion engine performance in a motor vehicle, comprising: means for monitoring a vehicle operating parameter and producing a vehicle operating parameter signal corresponding to an operational state thereof; and a control computer responsive to said vehicle operating parameter signal to assess a penalty corresponding to a predefined interval of lower available engine performance if said operational state of said vehicle operating parameter signal is inconsistent with a predefined fuel economy goal for a predetermined interval of vehicle operation, said control computer accumulating said penalties and adjusting available engine performance in accordance with the cumulative penalty value.
 38. A method of controlling an internal combustion engine in a motor vehicle, comprising the steps: monitoring the fuel economy of said engine; establishing a speed incentive mode of operation in which the maximum allowable vehicle speed is automatically adjusted in a range of speeds as an increasing function of monitored fuel economy; and providing a maximum allowable vehicle speed above the low end of said range when said speed incentive mode is disabled.
 39. The method of claim 38 wherein said speed incentive mode is enabled by inputting vehicle speed into an engine control computer in an engine performance parameter programming step.
 40. The method of claim 39 wherein said range includes at least a low speed value, a high speed value, and a default speed value therebetween.
 41. The method of claim 40 wherein the maximum allowable vehicle speed is adjusted as a discrete function of monitored fuel economy.
 42. The method of claim 40 wherein the maximum allowable vehicle speed is adjusted as a continuous function of monitored fuel economy.
 43. A method of controlling an internal combustion engine in a motor vehicle, comprising the steps: monitoring at least one vehicle operating parameter over a predetermined distance of vehicle operation; increasing available engine performance if the value of said at least one vehicle operating parameter over said predetermined distance is consistent with a predetermined vehicle fuel economy goal; decreasing available engine performance if the value of said at least one vehicle operating parameter over said predetermined distance is inconsistent with said predetermined vehicle fuel economy goal.
 44. The method of claim 43 wherein said increasing step includes increasing one of available engine output power and available vehicle speed; and wherein said decreasing step includes decreasing one of available engine output power and available vehicle speed.
 45. The method of claim 44 wherein the motor vehicle includes a transmission operatively connected to the engine and having a plurality of gears selectably engageable with the engine; and wherein said at least one vehicle operating parameter includes the transmission gear selection.
 46. The method of claim 45 wherein said increasing step includes increasing available engine performance if the presently engaged transmission gear corresponds to a numerically highest one of the plurality of transmission gears for more than a predetermined percentage of said predetermined distance.
 47. The method of claim 46 wherein said decreasing step includes decreasing available engine performance if the presently engaged transmission gear corresponds to a numerically highest one of the plurality of transmission gears for less than a predetermined percentage of said predetermined distance. 